[RFA 1/5] Add class scoped_switch_auto_to_sym_language.

[Philippe Waroquiers <philippe.waroquiers@skynet.be>]

The class scoped_switch_auto_to_sym_language allows to switch in a scope
the current language to the language of a symbol when language mode is
set to auto.

2018-10-27  Philippe Waroquiers  <philippe.waroquiers@skynet.be>

	* language.h (scoped_switch_auto_to_sym_language): new class.
---
 gdb/language.h | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/gdb/language.h b/gdb/language.h
index 02a84ff9a2..47a88de756 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -707,4 +707,43 @@ private:
   enum language m_lang;
 };
 
+/* If language_mode is language_mode_auto,
+   then switches current language to the language of SYM
+   and restore current language upon destruction.
+
+   Else does nothing.  */
+
+class scoped_switch_auto_to_sym_language
+{
+public:
+
+  explicit scoped_switch_auto_to_sym_language (const struct symbol *sym)
+  {
+    if (language_mode == language_mode_auto)
+      {
+	m_lang = current_language->la_language;
+	m_switched = true;
+	set_language (SYMBOL_LANGUAGE (sym));
+      }
+    else
+      m_switched = false;
+  }
+
+  ~scoped_switch_auto_to_sym_language ()
+  {
+    if (m_switched)
+      set_language (m_lang);
+  }
+
+  scoped_switch_auto_to_sym_language
+      (const scoped_switch_auto_to_sym_language &)
+      = delete;
+  scoped_switch_auto_to_sym_language &operator=
+      (const scoped_switch_auto_to_sym_language &) = delete;
+
+private:
+  bool m_switched;
+  enum language m_lang;
+};
+
 #endif /* defined (LANGUAGE_H) */
-- 
2.19.1